US3321713A - Frequency stabilized multivibrator - Google Patents

Frequency stabilized multivibrator Download PDF

Info

Publication number
US3321713A
US3321713A US539846A US53984666A US3321713A US 3321713 A US3321713 A US 3321713A US 539846 A US539846 A US 539846A US 53984666 A US53984666 A US 53984666A US 3321713 A US3321713 A US 3321713A
Authority
US
United States
Prior art keywords
multivibrator
frequency
transistors
thermistor
variations
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US539846A
Other languages
English (en)
Inventor
Johansson Hans
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BILLMAN REGULATOR AB
Original Assignee
BILLMAN REGULATOR AB
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by BILLMAN REGULATOR AB filed Critical BILLMAN REGULATOR AB
Application granted granted Critical
Publication of US3321713A publication Critical patent/US3321713A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K3/00—Circuits for generating electric pulses; Monostable, bistable or multistable circuits
    • H03K3/02—Generators characterised by the type of circuit or by the means used for producing pulses
    • H03K3/26—Generators characterised by the type of circuit or by the means used for producing pulses by the use, as active elements, of bipolar transistors with internal or external positive feedback
    • H03K3/28—Generators characterised by the type of circuit or by the means used for producing pulses by the use, as active elements, of bipolar transistors with internal or external positive feedback using means other than a transformer for feedback
    • H03K3/281—Generators characterised by the type of circuit or by the means used for producing pulses by the use, as active elements, of bipolar transistors with internal or external positive feedback using means other than a transformer for feedback using at least two transistors so coupled that the input of one is derived from the output of another, e.g. multivibrator
    • H03K3/282—Generators characterised by the type of circuit or by the means used for producing pulses by the use, as active elements, of bipolar transistors with internal or external positive feedback using means other than a transformer for feedback using at least two transistors so coupled that the input of one is derived from the output of another, e.g. multivibrator astable
    • H03K3/2823—Generators characterised by the type of circuit or by the means used for producing pulses by the use, as active elements, of bipolar transistors with internal or external positive feedback using means other than a transformer for feedback using at least two transistors so coupled that the input of one is derived from the output of another, e.g. multivibrator astable using two active transistor of the same conductivity type

Definitions

  • the present invention relates to multivibrators and particularly to means therein for securing frequency stability by means of a thermistor.
  • a known great problem in connection with oscillation generators in general is the difliculty of maintaining the frequency stable.
  • External influences such as temperature variations of the ambient atmosphere, as well as the characteristics of the components forming part of the oscillator often affect the generated frequency adversely.
  • said drawback can be eliminated merely by the use of a considerable number of well chosen components having an extremely good quality, particularly in respect of temperature insensitivity and aging.
  • the present invention presents another solution of the problem of creating an oscillation generator satisfying servere demands in respect of frequency stability and requiring merely a small number of low-cost components, and the main feature, whereby said object is reached, consists in the insertion of a negative thermistor in the emitter circuit of at least one of the transistors.
  • the drawing shows a bi-stable multivibrator generating a voltage of square wave shape between the output terminals 3, 4.
  • the multivibrator comprises two transistors T1 and T2, each one having its base electrode con nected to the collector electrode of the other transistor via a condenser C2 or C3. Said condensers together with the resistors R4, R determine the natural frequenc of the multivibrator which is also dependent to some extent upon the leakage currents of the transistors and upon the voltage remaining between the collector and the negative terminal when the transistors are conductive. Silicone transistors are preferred for the present use, because said kind of transistors show very small leakage currents, so that it is possible in practice to disregard them when calculating the natural frequency of the multivibrator.
  • the multivibrator shown is meant to be used for driving a synchronous timepiece, and therefore it is completed with means for synchronization with the frequency of the general power supply system (the mains) and with means for charging an accumulator A. In case of failure of the mains, said battery takes over the power supply of the multivibrator.
  • the mains terminals 1, 2 are connected to two opposite diagonal points of a full-Wave rectifier bridge L, the other two diagonal points of which are connected to output terminal 4, one of them directly and the other one via resistors R1, R2 and the accumulator A.
  • Condenser C1 serves for smoothing the rectified current.
  • Via emitter resistors R7, R8 the emitter electrodes of the transistors are connected to terminal 4, and via resistors R9, R10 and condensers C4, C5 their base electrodes are connected each to a separate one of the mains terminals 1, 2. Due to said latter connection the mains frequency is applied to the two base electrodes and forces the multivibrator to deviate slightly from its natural frequency so as to oscillate in synchronism therewith.
  • a thermistor RT in parallel to the emitter resistor R7 there is connected a thermistor RT consisting of a semiconductive member, the resistance of which has a negative temperature coelficient, i.e. its resistance value drops with rising temperature.
  • a heating resistor R11 Adjacent said thermistor there is placed a heating resistor R11 which in series with the resistors R1, R2 is connected in the line connecting the rectifier bridge L to one pole of the accumulator and carrying the charging current.
  • the base electrodes of the transistors are connected to said pole via the resistors R4, R5, and the collector electrodes of the transistors are connected thereto via the collector resistors R3, R6.
  • the temperature coeflicient of the condensers forming part of the multivibrator is negative.
  • the temperature coeflicient of the components involves a corresponding ferquency variation, the direction of which is such that the frequency rises when the ambient temperature rises.
  • a component having a great positive temperature coeflicient might have been useful, but in the present case there is no such component available that is suitable.
  • the present invention is based upon the principle of obtaining the compensation by influencing the voltage remaining between the collector electrode and the negative pole of a transistor when conductive.
  • the magnitude of said voltage can be influenced by vary ing the resistance in the emitter circuit of the transistor.
  • the desired result is obtained by associating a negative thermistor with the common emitter resistor.
  • the oscillation frequency is determined by the expression 1 f #1 2 wherein t and t are the two parts forming together the time period of a full cycle. If said part time periods could be held constant, f would also be held constant.
  • the part times can be expressed as follows:
  • the pulse-interval-ratio is not decisive to any significant extent, compensation of merely one of the emitter circuits of the transistors will suffice.
  • the frequency drift still remaining after the introduction of said compensation is very slight, under the provision that the thermistor is properly dimensioned and that the variation of the ambient temperature lies within the range of 10 to 60 degrees centigrade.
  • the oscillation frequency should be adjusted to 60 cycles per second as closely as possible.
  • the multivibrator is forcefully synchonized by the mains frequency, as above described, but then the natural frequency of the multivibrator should be adjusted to a lower value than the mains frequency.
  • the natural frequency of the multivibrator is lowered, when connected to the mains, by having the above-mentioned resistor R11 heat the thermistor RT used for the temperature compensation.
  • the natural frequency of the multivibrator is adjusted to deviate about 2 c./s. from the frequency of the mains as soon as the resistor R11 is heating the thermistor.
  • Circuit for stabilizing the frequency of a multivibrator subjected to variations of the ambient temperature comprising two transistors having their base and collector electrodes mutually cross-connected via frequency determining members, characterised in that the emitter circuit of at least one of the transistors comprises a negative thermistor, whereby variations of the ambient temperature will bring said thermistor to influence the emitter voltage in such a manner as to compensate the variations of the collector voltages of the tran sistors caused by said temperature variations.
  • Circuit as claimed in claim 1 characterized in that the thermistor is connected in parallel to a common emitter resistor.
  • Circuit as claimed in claim 1 characterized in that a heating resistor is placed in heat transferring relation to the thermistor.
  • Circuit as claimed in claim 1 characterized in that the base electrodes of the transistors via suitable circuit members are connected each to a separate one of the terminals of a power supply system in order to synchronize the frequency of the multivibrator with that of said system.
  • a multivibrator circuit comprising two transistors, each one having its base electrode connected via a condenser to the collector electrode of the other transistor and having its emitter electrode connected via an emitter resistor to one and the same terminal of a current supply source, the collector and base electrodes of the transistors being connected via separate resistors to the other terminal of said source, a thermistor being connected in parallel to said emitter resistor of one of the transistors, said thermistor having a negative resistance coefficient, whereby frequency variations of the multivibrator caused by changes of the ambient temperature are compensated.
  • Multivibrator circuit as claimed in claim 5, in which said current source consists of an accumulator charged by an A.C. power network via a rectifier bridge, characterised in that each of the base electrodes of the transistors is connected via coupling members to a separate one of the terminals of said A.C. network, whereby the frequency of the multivibrator is synchronized with said network when under tension.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • General Induction Heating (AREA)
  • Oscillators With Electromechanical Resonators (AREA)
US539846A 1965-04-13 1966-04-04 Frequency stabilized multivibrator Expired - Lifetime US3321713A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
SE4876/65A SE303790B (enEXAMPLES) 1965-04-13 1965-04-13

Publications (1)

Publication Number Publication Date
US3321713A true US3321713A (en) 1967-05-23

Family

ID=20265178

Family Applications (1)

Application Number Title Priority Date Filing Date
US539846A Expired - Lifetime US3321713A (en) 1965-04-13 1966-04-04 Frequency stabilized multivibrator

Country Status (3)

Country Link
US (1) US3321713A (enEXAMPLES)
DE (1) DE1267709B (enEXAMPLES)
SE (1) SE303790B (enEXAMPLES)

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None *

Also Published As

Publication number Publication date
SE303790B (enEXAMPLES) 1968-09-09
DE1267709B (de) 1968-05-09

Similar Documents

Publication Publication Date Title
US3742384A (en) Variable frequency oscillator
GB529383A (en) Improvements in or relating to thermionic valve circuits for the generation of saw tooth currents
ATE99435T1 (de) Stabiler referenzspannungsgenerator.
GB1467126A (en) Current stabilizing arrangement
KR950007296A (ko) 기준전압 발생회로용 정정 회로
US3321713A (en) Frequency stabilized multivibrator
EP0370364A1 (en) Voltage reference circuit with linearized temperature behavior
US3526853A (en) Frequency stabilized multivibrator
US3144599A (en) Three-phase static inverter
US2920258A (en) Voltage arrangement
GB902078A (en) Improvements in or relating to electronic relays
US2769906A (en) Junction transistor oscillator circuits
SU796819A2 (ru) Стабилизатор посто нного напр жени
SU1328260A1 (ru) Электровибрационное устройство к загрузочному бункеру
US4173040A (en) DC-to-AC voltage converter
RU18605U1 (ru) Преобразователь напряжения
SU1001057A1 (ru) Стабилизатор посто нного напр жени
US1898932A (en) Alternating current generator
SU111255A1 (ru) Стабилизатор напр жени посто нного тока
SU424125A1 (ru) Стабилизатор высокого напряжения с температурной компенсацией
SU408431A1 (enEXAMPLES)
KR860001705B1 (ko) 고전압 가열장치의 정수배주기파형 발생회로
SU758096A1 (ru) Стабилизатор высокого напряжения с температурной компенсацией
TW392332B (en) Self-biased voltage-adjusted current source
SU1003306A1 (ru) Мультивибратор